You want to connect your laptop and an Android phone or tablet? You do not need a code to 'connect' using an emulator or USB. You do need the code to connect to a phone/tablet.
Have you installed the aiCompanion onto your tablet from Google Play? Once you have done that, you can use WIFI to connect the tablet to the Android.
From the AI2 Browser screen, go to Connect > AI Companion a screen will appear with the six digit code (the code is different every time you connect). On you Android device, start the MIT App Inventor 2 Companion that you installed. There is a place to type the code on the aiCompanion opening screen (where it indicates Six Digit Code). Type the code .. it is not six digits, but it is the six alphabetical lower case characters you see on your laptop. Type the letter (Do NOT type a carriage return (Enter)) then touch the orange "connect with code" button on the app.
Did that work for you?
Please let us know what happens and if you get this working.
Regards,
Steve